[Leaplist] major bug found in Linux to give root access to untrusted users...

[Ray Brunkow]

Edward Guldemond wrote:
> On Wed, Nov 04, 2009 at 12:26:49PM -0500, Ray Brunkow wrote:
>   
>> is this as bad as it sounds?
>>     
>
> Check to see if your vm.mmap_min_addr sysctl is set to a value above
> 0.  On my system (Debian), it's as simple as:
>
>         $ sudo sysctl -n vm.mmap_min_addr
>         4096
>
> So my system is safe.  Check yours.  If it's not greater than zero,
> then use sysctl to set it to something greater than zero:
>
>         $ sudo sysctl -w vm.mmap_min_addr=4096
>
> And put that in a startup script until your disto fixes it or you're
> using a patched kernel (though 4096 is a safe default setting).
>
> vm.mmap_min_addr, as the name implies, is the minimum memory address
> that a process can mmap(), and it's tunable.  What this means is that
> a process will not be allowed to mmap() at 0, thus preventing the NULL
> pointer dereference attack.
>
>   
> ------------------------------------------------------------------------
>
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>   
so this is safe:

sysctl -n vm.mmap_min_addr
65536


-- 
Raymond L. Brunkow
5th Degree Black Belt
Certified Instructor
Choong Sil Kwan TaekwonDo Federation


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